United States Patent Office 3,412,360 Patented Nov. 19, 1968 3,412,360 ANGULARLY ADJUSTABLE CONTROL Michael Heath Colburn, Milwaukee, Wis., assignor to Globe-Union Inc., Milwaukee, Wis., a corporation of Delaware Filed June 23, 1965, Ser. No. 466,349 10 Claims. (Cl. 338-162) ABSTRACT OF THE DISCLOSURE A rotary electrical control is described. The driven element of the control is mounted on a first shaft which is threaded to a second shaft with a pliable insert to increase the friction. The second shaft is connected to a control shaft with a coupling allowing relative axial displacement but insuring a firm rotational drive. The control shaft is connected to a detent indexing mechanism. Rotation of the control shaft causes rotation of the driven element but the driven element may be rotated relative to the control shaft through the threaded coupling to permit angular adjustment.

The present invention relates in general to a variable electrical component and more specifically to a mechanism for use in a variable electrical component. While not so limited in its uses, the present invention finds particular advantageous utilization in connection with variable resistors.

A primary object of the present invention is to provide a new and improved variable electrical component. Another primary object is to provide a new and improved mechanism for use in a variable electrical component.

A more specific object of the present invention is to provide a new and improved mechanism for a variable electrical component which allows for rotating a control shaft and a control element thereof relative to one another. Another object is to provide a variable electrical component employing such a mechanism which is adapted for use with an index assembly. A related object is to provide such apparatus wherein the control shaft is associated with the index assembly and the mechanism allows for rotation of the control element relative to the control shaft when the control shaft is held in place by the index assembly. Another related object is to provide such apparatus which allows for varying the component value and for calibrating the component subsequent to installation thereof.

A general object of the present invention is to provide a new and improved variable electrical component characterized in its simplicity and economy. Another general object is to provide a new and improved mechanism for use with a variable electrical component which is likewise characterized in its simplicity and economy.

Other objects and advantages of the invention will become apparent upon reading the attached detailed description taken in conjunction with the drawing.

In one form of the present invention a variable electrical component is provided which includes a rotatable control element and a rotatable control shaft. A member constructed in accordance with the teachings of the present invention is provided which includes first and second shafts drivingly connected to the control shaft and the control element so that the control element is rotated when rotational movement is imparted to the control shaft and which is adapted to allow the control element to be rotated relative to the control shaft.

The present invention will now be described in conjunction with the drawing wherein:

FIGURE 1 is a sectional side-elevational view of a variable resistor assembly including an indexing assembly section and a variable resistor section which employs a mechanism constructed in accordance with the teachings of the present invention;

FIG. 2 is a view showing facing surfaces of a portion of the variable resistor section shown in FIG. 1;

FIG. 3 is an end view of a first shaft forming a part of the mechanism shown in FIG. 1;

FIG. 4 is an end view of a second shaft forming a part of the mechanism shown in FIG. 1; and

FIG. 5 is a sectional view of the second shaft taken substantially along line 55 in FIG. 1.

While the invention has been shown and will be described in some detail with reference to a particular exemplary embodiment thereof, there is no intention that it be limited to such details. Quite to the contrary it is intended here to embrace all modifications, alternatives and equivalents falling within the spirit and scope of the invention as defined by the appended claims. The mechanism constructed in accordance with the teachings of the present invention will be described in conjunction with a variable resistor. However, it will be readily apparent to those skilled in the art that the mechanism is adapted for use in conjunction with any variable electrical component or the like wherein it is desired to adjust the relative position of two rotatable elements.

Referring now to the drawing and more specifically to FIG. 1, a new and improved variable electrical component is shown which employs a mechanism constructed in accordance with the teachings of the present invention. The exemplary component includes a variable resistor 11 and an index assembly 12.

The variable resistor 11 (FIGS. 1 and 2) includes a cup-like main outer housing or cover 13. A stator 14 and a rotatable control element or rotor 15 are mounted within the housing 13 and are maintained therein by a front plate 17 which is suitably secured to the housing to close the open end thereof. As may be seen, a bushing 18 is associated with the front plate 17. The control element or rotor 15 and the stator 14 are formed of a nonconductive material, such as phenolic, and are mounted so that the rotor may be rotated relative to the stator. A control shaft 20 is provided for imparting rotational movement to the rotor 15, as will become apparent. The rotor 15 has a rearwardly extending projection 15' which is adapted to engage a stop 13a formed as part of the housing 13 so that the rotor is limited to rotation through one revolution. The stator 14 has an inner conductive contact ring 14a mounted thereon which is electrically connected to a radially extending output terminal 21 and which is engaged by a resilient contact 1512 mounted on the rotor 15. Additionally, the stator 14 has an outer ring of resistive material 14b mounted thereon which is electrically connected to radially extending output terminals 22 and which is engaged by a resilient contact 15b mounted on the rotor. The resilient contacts 15a and 15b mounted on the rotor 15 are electrically connected together so that a circuit is completed thereby between the inner and outer rings 14a and 14b on the stator.

In view of the foregoing, it will be apparent that a resistance will be provided between output terminals 21 and 22 which is dependent upon the position along the ring of resistive material 14b with which the resilient contact 15b is in engagement. Moreover, it will be apparent that the resistive value provided between terminals 21 and 22 may be varied by imparting rotational movement to the rotor 15 and thus by varying the position along the ring of resistive material 14b with which the resilient contact 15b is in engagement.

In the exemplary arrangement, a ball detent type indexing assembly 12 (FIG. 1) is associated with the control shaft 20 so that rotational movement of the control shaft is controlled thereby. More specifically, the control shaft 20 is normally held substantially rigidly in place by the indexing assembly. The indexing assembly is mounted in spaced relationship with the variable resistor 11. The ball detent assembly includes a hub 24 through which the control shaft 20 extends. A plate 25 is fixedly secured to the hub 24 in any suitable manner as by a rolled connection 26 and the plate 25 is fixedly secured to a support plate 27 associated with the variable resistor 11. The support plate 27 is suitably secured to the bushing 18 such as by a Tinnerman fastener 28 which is received in a circumferential groove 18a provided in the bushing. The plate 25 may, for example, be secured to the plate 27 by means of bolts 31 extending through aligned apertures in the plates 25 and 27, with cylindrical spacers 32 being carried by the bolts to maintain the plates in generally parallel spaced relationship. Additionally, the index assembly 12 includes a small plate 33 telescoped on the shaft 11 and held against axial movement along the shaft toward the variable resistor 11 by staked shaft portions 20a, thus holding shaft 20 against movement through the hub 24 in a direction to the right as viewed in FIG. 1. A C-washer 34 received in a circumferential groove 20b. in the shaft 20 prevents movement of the shaft in an opposite direction. Since the ball detent type indexing mechanism 12 is of the conventional type and does not constitute a portion of the present invention, further details thereof will not be set forth herein.

In accordance with the present invention a mechanism is provided for connecting the control shaft 20 to the control element or rotor so that the rotor is rotated with the control shaft and may be rotated relative to the control shaft when the control shaft is held in place by the indexing mechanism 12. In its exemplary form the mechanism includes a first shaft 36 drivingly connected to the control shaft and a second shaft 37 drivingly connected to the rotor 15. As may be seen, the shaft 36 extends through bores provided in the bushing 18, the front plate 17 and the stator 14. For the purpose of drivingly connecting the first shaft 36 to the control shaft 20 a radial slot 36a is provided in the forward or right-hand end of the shaft 36 as viewed in FIG. 1 and the control shaft 20 is provided with a rearwardly extending radial projection 20c which is adapted to be keyed to or received in the radial slot 36a of the shaft 36. For the purpose of drivingly connecting the second shaft 37 to the rotor 15 the shaft 37 is provided with an intermediate portion 37a which has a frusto-circular cross section as shown in FIG. 4 and which is received within a corresponding aperture 150 extending through the rotor 15. In other words, the intermediate portion 37a of the shaft 37 and the aperture 150 of the rotor 15 have cross sections corresponding to a circle having diametrically opposite segments removed therefrom to define flat or straight side portions and the portion 37a is drivingly received within the aperture 15c.

In keeping with the present invention, the shaft 36 and the shaft 37 are connected together so that they may be rotated together or rotated relative to one another. For this purpose, the shaft 37 is provided with a threaded portion 37b (see FIGS. 1 and 4) which is threadedly received within a threaded bore 36b provided in the shaft 36 (see FIGS. 1 and 3). Consequently, the shafts 36 and 37 may be rotated relative to one another by threading the portion 37b of the shaft 37 into or out of the bore 36b of the shaft 36.

For this latter purpose, the shaft 37 extends rearwardly of the variable resistor 11 through an aperture 13b prov-ided in the housing 13 and the shaft 37 is provided with a rearwardly extending radial slot 370. Accordingly, an object such as a screwdriver may be inserted within the slot 370 so that rotational movement may be imparted to the shaft 37 from the rear of the variable resistor 11. Since the control shaft 20 is normally held substantially rigidly in place by the index mechanism 12 and the shaft 4 36 is drivingly connected to the control shaft 20, it will be readily apparent that, when rotational movement may be imparted to the shaft 37 from the rear of the variable resistor, the shaft 37 is rotated relative to the shaft 36 so that the rotor or control element 15 is rotated relative to the control shaft 20. V I

Thus, the mechanism allows for calibration of the rotor 15 with respect to the control shaft 20.

On the other hand, it is desirable for the shafts 36 and 37 to be rotated together when rotational movement is imparted to the control shaft20 so that the rotor 15 is rotated simultaneously with the control shaft 20 and the variable resistor 11 is thereby varied. To insure such concurrent rotational movement, a radial bore 37d (FIG. 5) is provided in the threaded portion 37b of the shaft 37 and an insert 40 formed of a pliable material is extended through the bore 37d so that it extends outwardly of the threaded portion 37b. In other words, the insert 40 is designed to be greater in length than the bore 37d. When the threaded portion 37b of theshaft 37 is threaded into the bore 36b of the clutch shaft 36, the insert 40 is compressed within the bore 37d and the insert exerts an outwardly directed binding force against the bore 36b of the shaft 36 which insures that the shafts 36 and 37 rotate together in the absence of some opposing force being applied to one of the shafts. The insert 40 may be constructed of a'material such as nylon and may be press fit into the bore 37d.

As previously mentioned, the exemplary rotor 15 has a projection 15' which engages a stop 13a to limit rotational movement of the rotor. The index assembly 12 is preferably also provided with stop means (not shown) which is the controlling stop means. In order to insure that calibration of the variable resistor 11 in such an arrangement is not lost subsequent to the calibration thereof by relative rotational movement of the shafts, the index assembly will be provided with a smaller angular sweep than the rotor 15 and the amount of calibration of the variable resistor will be limited by the difference between the angular sweeps of the index assembly and the rotor. However, the invention may be readily modified to eliminate this limitation and, therefore, the invention is not intended to be limited to such detail.

In view of the foregoing it will be seen that a new and improved variable resistor element has been provided. More specifically, it may be seen that a mechanism is provided for utilization in connection with a variable electrical component such as a variable resistor. Moreover, it will be seen that a mechanism has been provided for use with a variable electrical component which allows for adjustment of the component to vary the value thereof and to calibrate the component even after the component has been secured to an indexing mechanism or the like.

I claim: a 1

'1. In a' variable component, the combination which comprises a rotatable control element having a varying electrical characteristic dependent upon its rotational position, a control shaft, means supporting said control shaft for rotational movement but preventing axial movement, axially displaceable means coupling the control shaft to the control element for causing the control element to be rotated with the control shaft when rotational movement is imparted tothe control shaft and for allowing the control element to be rotated-relative to the control shaft whereby the electrical characteristic of'said control element may be varied by' rotating said control shaft or by rotating said control eleznent relative to said control shaft. I?

2. In a variable electrical component, the combination which comprises a rotatable control'elernent having a varying electrical characteristic dependent "upo'n its rotational position, a control shaft, firstand second'axially aligned shafts drivingly connected respectively toithe control shaft and to the control element, means for coupling said first and second shafts for causing the control element to be rotated with the control shaft when rotational movement is imparted to the control shaft and for allowing the control element to be rotated relative to the control shaft whereby the electrical characteristic of said control shaft or by rotating said second shaft relative to said first shaft and said control shaft.

3. In a variable electrical component, the combination which comprises a rotatable control element having a varying electrical characteristic dependent upon its rotational position, a control shaft, a first shaft having a threaded bore formed therein and drivingly connected to the control shaft, a second shaft having a threaded portion extending therefrom which has a radial bore, and an insert formed of a pliable material positioned in the radial bore which is greater in length than the radial bore, the threaded portion being threadably received in the threaded bore and the insert allowing the first and second shafts to be rotated together with said control shaft and to be rotated relative to one another, the second shaft being drivingly connected to the control element whereby the electrical characteristic of said control element may be varied by rotating said control shaft or by rotating said second shaft relative to said first shaft and said control shaft.

4. The component as recited in claim 3 wherein the radial bore extends through the threaded portion.

5. The component as recited in claim 3 wherein the insert is formed of nylon.

6. A variable rotary component including a driven member threaded to a shaft, means for rotating said driven member relative to said shaft, a driving member coupled to said shaft through a rotary drive connection allowing relative axial displacement of said driven member and shaft, said driven member having a relatively fixed axial position with respect to said driving member,

said driven member, said shaft, and said driving member being in axial alignment with one another.

7. The component of claim 6 further including means for increasing the friction at the threaded connection between said shaft and driven member.

8. The component of claim 7 wherein said means includes a resilient material carried by the threaded portion of said connection.

9. The component of claim 6 further including a housing in which said driving member is rotatably mounted and a detent for increasing the resistance to rotation between the driving member and the housing.

10. The component of claim 6 wherein said connection is a longitudinally extending slot on one of the coupled members and a longitudinal extension on the other of the coupled members, said extension and slot engaging one another.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION atent No. 3,412,360 November 19, 1968 Michael Heath Colburn It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below: Column 4, line 21, before "shaft cancel "clutch. Column 5, line 4, after "control" insert element may be varied by rotating said control Signed and sealed this 31st day of March 1970.